Powder layer density
Smaller powder sizes with higher relative powder densities require less energy to sinter. A wider distribution of particles sizes can also allow for higher powder density, since smaller particles can fill the gaps between larger particles. McGeary  demonstrated that specific ratios of bi-modally distributed powder sizes can achieve an optimal packing density of 84 % with a 1:7 size ratio and a 30 % weight fraction consisting of the smaller size.
However, if the amount of fine particles, (<6/10μm) is too high, the agglomeration of particles can eliminate their positive effects of filling up voids. These particles can present health and safety risks as their handling trigger creation of 'dust' cloud.
Theoretical layer thickness = 30um (effective layer thickness =47um)
- Energy input insufficient to fully melt the larger particles (not fully irradiated)
- Partially unmelted coarser particles generates voids within the scanned layer
- Emerging surface roughness promotes inability to fill the valleys between the scan tracks of the last layer
Theoretical layer thickness = 45um (effective layer thickness =74um)
- the energy flux is reduced quickly with increasing layer thickness
- when effective layer thickness is >> theoretical layer thickness, amount of fine powder grains becomes comparatively less important.
- the effective powder layer thickness teff must be at least 50% higher than the diameter of 90% of the powder particles so that most of the particles can be deposited within teff: teff > 1.5 x D90
- Sufficient amount of fine particles are necessary to fill the voids between the coarser grains. D90 > 5x D10
- Both requirements together indicate that D10 is about 7.5 times smaller than teff
 A. Strondl, O. Lyckfeldt, H. Brodin, and U. Ackelid, “Characterization and Control of Powder Properties for Additive Manufacturing,” Jom, 2015.
 Karapatis, N.P., A sub-process approach of selective laser sintering. 2002, Ecole Polytechnique fédérale de Lausanne EPFL: Lausanne.
 Karapatis, N.P., G. Egger, P.-E. Gygax, and G. Glardon. Optimization of Powder Layer Density in Selective Laser Sintering. in Proc. Of the 9th Solid Freeform Fabrication Symposium. 1999. Austin (USA).
 I. Robertson and G. Schaffer, “Some effects of particle size on the sintering of titanium and a master sintering curve model,” Metall. Mater. Trans. A, vol. 40, no. 8, pp. 1968–1979, 2009.
 H. Su and D. L. Johnson, “Master sintering curve: A practical approach to sintering,” J. Am. Ceram. Soc., vol. 79, no. 12, pp. 3211–3217, Dec. 1996.
 Comparison of density of stainless steel 316L parts produced with selective laser melting using different powder grades, A. B. Spierings, G. Levy, SFF Symposium 2009 Review Paper